Compensating friction in electric meters.



PATENTEI) JUNE 30, 1903.

I. P. COX. CCMPENSATING FRICTION IN ELECTRIC METERS.

APPLICATION TILED JAN. 22. 1902. RENEWED APB. 27.1903.

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s P YER/5 co. Pno-mumo. WliNlNGT Patented June 30, 1903.

UNITED STATES PATENT 4 OFFICE.

FRANK P. COX, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIC COMPANY, A CORPORATION OF NEW YORK.

.COMPENSATING FRICTION IN ELECTRIC METERS.

SPECIFICATION formingpart of Letters Patent No. 732,176, dated June 1903- Application filed January 22, 1902. Renewed April 27, 1903. Serial No. 154,575 (No model.)

To all whom it may concern:

- Be it known that I, FRANK P. COX, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Compensating Frictionin Electric Meters, of which the following is a specification.

In operating electric Wattmeters in order to improve the accuracy of the readings an auxiliary coil is employed to impart a sufficient tendency to motion to just balance the frictional opposition to starting, thus rendering the mechanism free to accurately respond to the load-current passing through the meter. It is desirable that this assisting force should be capable of a certain range of adjnstment to adapt it to difierent individual mechanisms, since it is evident that no two devices or conditions of installation under which such devices operate will be exactly identical.

My invention relates to an improved starting device of this character.

In carrying out the invention I provide an auxiliary coil mounted in operative relation to the armature which drives the recording mechanism and adapted to slide to or fro with relation to the armature, so that its assisting effect may be varied to accurately adjust the instrument to which it is attached. I prefer to connect this coil in the shunt or potential circuit of the wattmeter where such is employed as, for example, in the wellknown Thomson recording-wattmeterand secure it to a guide by which it may be shifted relatively to the series field-coils of the wattmeter which carry the load-current. I have found by experience that a coil of this character adapted to slide to or fro over parallel planes is more satisfactory, by reason of its simplicity of construction and compactness and closeness to the armature, than other devices heretofore proposed for this purpose.

My invention therefore comprises a device for compensating friction in recording-wattmeters and the like, consisting of an electromagnetic device capable of reacting upon the motor-armature so as to assist its movement, mounted so as to slide to or from the armature to augment or diminish the assisting effect. In a more specific sense it embodies an assisting-coil mounted so as to be adjustable coils and a starting-coil embodying my improvements.

As shown in the drawings, the device is mounted upon a recording-wattmeter of the well-known Thomson type, comprising an air-core armature connected in a potentialcircuit, as well understood, and rotating in a magnetic field established bya pair of series coils 1 1. The speed of the motor driving the recording mechanism shown at the top is dampened by permanent magnets, as 2, in the field of which rotates a conducting-disk mounted upon the same shaft as the armature. This construction is of general adoption in the art and will not require a detailed description.

The starting-coil is shown at 3 and comprises a coil of fine wire, which Iprefer to connect inseries with the armature on the potential-circuit, of such a size that it may slide within the field-coils, as indicated in Fig. 2. The adjustment may be effected by means of a metal adjustment-strip 4, clamped toaspider or plate 5, secured to the coil, a threaded pin 6 being fastened to such plate and extending through a hole in the bent end of the strip 4, being secured thereon by means ofa clamp-screw, as indicated in Fig. 2. Thus when the adjustment-strip is fastened to the coil the latter may be moved in and outwith relation to the armature by the fprojecting tongue and may be clamped in position by a thumb-nut 7, engaging a screwQto the inner end of which is secured a band or stirrup supporting the strip 4. Beneath the nut may be placed a plate 8. Thus the startingcoil when properly positioned may be clamped fast by turning the thumb-nut, and thus binding the adjusting-strip 4 against the fieldcoils. The spider or plate 5 may be fastened to the compensating coil in any satisfactory way. As shown in the drawings, the plate is pierced with a series of holes, through which a cord is passed and suitably fastened.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is

1. A metermotor provided with a fieldmagnet and armature coils, and an auxiliary starting-coil adjustable within said field-coil and parallel thereto.

2. A meter-motor provided with a fieldmagnet and armature, and an auxiliary coil to compensate friction supported on the fieldcoil and adjustable within said field-coil in a straight line toward and away from the armature.

3. A meter-motor provided with a startingcoil in addition to its armature and field-magnet coils, said starting-coil being mounted to slide within the field-coil to or from the armature, and means for securing it in any position of adjustment throughout its range of movement.

4. A meter-motor comprising field-magnet and armature coils, and an auxiliary startingcoil to balance friction mounted in sliding relation to the field-coil, and adapted to nest within the same.

5. In a meter, a starting-coil to compensate friction, an arm secured thereto, and means for clamping said arm to hold the coil in ya rious positions.

6. In a meter, a starting-coil to compensate coils in various positions.

8. In a meter, a pair of field-coils, an armature between the field-coils, an adjustable starting-coil, an arm secured thereto, a clamp ing device between the field-coils, and a wingnut for regulating the same, said device being adapted to clamp said arm to hold the starting-coil in any position throughout its range of adjustment.

In witness whereofI have hereunto set my hand this 18th day of January, 1902.

FRANK P. COX.

Witnesses:

JOHN A. MCMANUS, DUGALD MoK. MCKILLOP. 

